Citation
Stylios, G.K. (2014), "Electrocarding technology: the manufacturing of nanoyarns for mass production of nanofabrics", International Journal of Clothing Science and Technology, Vol. 26 No. 3. https://doi.org/10.1108/IJCST-06-2014-0075
Publisher
:Emerald Group Publishing Limited
Electrocarding technology: the manufacturing of nanoyarns for mass production of nanofabrics
Article Type: Editorial From: International Journal of Clothing Science and Technology, Volume 26, Issue 3
Although the global market for nanofibre products is growing rapidly and is predicted to reach $2.2 billion in 2020 with an annual growth rate CAGR of 30.3 per cent (2012-2017), most of the activity thus far has been in small-scale production of niche products. Hence high-production costs, high-value goods and lower volume sales hinder demand.
The main nanoproducts being produced nowadays are in hygiene, air and water filtration, environmental protection and food and packaging characterised by high-surface area, high porosity and mechanical strength. The real challenge, however, is whether nanofibres can be converted into nanoyarns, enabling mass manufacturing of products that will leapfrog the textile industry, create wealth, improve life and sustain competition.
The difficulty of controlling the collection of the disorderly spun nanofibres render them unable to be formed into highly oriented bundles for spinning them into nanoyarns, and many research efforts for spinning nanofibres have been unsuccessful. This is the main reason of not making a leap forward in the construction of products. The ideal solution of connecting and integrating nanofibre production with conventional yarn spinning and subsequently weaving, knitting and braiding manufacture of industrial as well as fashion is yet to be discovered. And it would also make economic sense if existing machinery, equipment and manufacturing methods can be used as they are currently without any modification; an ideal scenario presented by many industrial strategists. This answer can be found in a new technology called electrocarding.
Electrocarding is the technology of facilitating the orderly collection of nanofibres into fibre web bundles and their conversion into nanosliver by fibre drawing, prior to yarn spinning. This new process has been invented in Scotland at the Research Institute for Flexible Materials of Heriot Watt University and protected by world patent; WO2011/015161 (G. Stylios and L. Luo). The possibilities for new products are vast and the technology is already regarded as the major step change for the textile industry in 30 years. New discoveries can be made in nanocomposites, nanobraids and nanotechnical fabrics for industrial applications; architecture, civil structures, geotextiles, automotive, shipping, military, medical and aerospace, and in new creations of nanoyarns, nanothreads, nanoknitwear fabrics, nanowovenwear fabrics, for fashion, apparel, upholstery and carpets. These new products underpinned by electrocarding technology can be IP protected and hence enable companies to compete globally. Companies can license their products abroad bringing revenue to local economy.
Electrocarding is based on the electrostatic principle of fibre carding. Nanofibres are usually electrospun by splitting a polymer drop into many nanofibres under very high voltage, these fibres are usually deposited on a collector in a disorderly manner and look as a non-woven mat, see Figure 1.
Figure 1 The mat-like nanofibres
But in electrocarding they are deposited on the surface of card wire covering a rotating drum and as they are assisted by the combination of electric pull and rotation, the nanofibres are formed into and orderly nanoweb bundle as shown in Figure 2. The proof of concept of the electrocarding principle has already been explored[1] by building a small laboratory size card drum 195 mm wide and 180 mm diameter, shown, capable of rotating via a DC motor between 10 to 40 rpm and being investigated by experimenting with nylon 6.
Figure 2 The electrocarding of nylon 6 nanofibres into an orderly nanosliver for yarn spinning
The fibres are collected in an orderly manner on the card of the drum as it rotates round, just like in wool carding and form webs of nanofibre bundles. These bundles can then be drawn by a series of doffing rollers to form a nanosliver/roving. From then on the art is the same, as practiced for hundreds of years, the nanofibre sliver/roving is collected and processed, with existing yarn equipment for nanoyarn manufacturing and subsequent knitting, weaving, finishing, etc.
To demonstrate this principle, we have used a yarn spinning wheel. The electrospun nanoweb was presented to the yarn spinning wheel where the bundle was drawn whilst twisted into yarn, as being practiced in some crafts today and being identical to power spinning (Figure 3).
Figure 3 Electrocarded nylon 6 fibre web being spun by a spinning wheel
Having produced an acceptable length of nanoyarn, samples were presented to the SEM for morphological investigation. Figure 4 is an SEM photograph showing a sample of twisted nylon 6 nanoyarn made by electrocarding. The morphology of another sample of nylon 6 nanoyarn under �250 magnification is shown in Figure 5, in which the high-density smooth surface of the nanoyarn is apparent, which gives it superior properties such as strength and absorption.
Figure 4 An SEM photograph showing a sample of nylon 6 nanoyarn made by the electrocarding technology process, in which the twist formation of the nanoyarn can be seen
Figure 5 The morphology of nylon 6 nanoyarn made by electrocarding technology, at �250 magnification
It is the process parameters, the functionality capabilities and the mixing compositions that will enable numerous products to be discovered, getting the textile industry to another era, without the need for any modification or investment in new machinery or process.
Although electrocarding has been tried and tested in the laboratory, it now needs optimising in a number of areas and the setting up of a pilot facility for integration with yarn spinning and fabric making, and hence pioneering the development of exciting new products.
George K. Stylios
Note
M.I. Yousef and P. Franco carried out the experiments, at the Research Institute for Flexible Materials of Heriot Watt University.